Measuring and length determining means for weft yarn in shuttleless looms

ABSTRACT

A shuttleless loom having a pneumatic delivery means and apparatus for measuring and determining the length of weft yarn fed thereto. The apparatus is adapted to pull a length of yarn from a supply, in cyclic action and hold the same under tension while being fed to the pneumatic means.

United States Patent 1191 Svaty 1 May 22, 1973 1 MEASURING AND LENGTHReferences C d DETERMINING MEANS FOR WEFT UNITED STATES PATENTS LE L SYARN IN F T SS M 3,626,990 12/1971 Linka ..139/122 R Inventor: Vladrmll'y, hlberec, 2,637,349 /1953 Dunham ..139/127 1? Czechoslovakla 3,229,725l/1966 Saito ......139/127 P Assigneez Elitex, z y textilniho strojirenMIZUUO Bi 8.1. P

stric generalnl reditelstvl, Liberac, FOREIGN PATENTS OR APPLICATIONSCzechoslovakia 583,830 /1958 Italy ..139/127 P [22] Filed: Oct. 9, 1970[21] Appl No; 79 478 Primary ExaminerHenry S. Jaudon AttorneyRichard Lowand Murray Schaffer Foreign Application Priority Data [57] ABSTRACT Oct.10, 1969 Czechoslovakia ..6777/69 A h l less m having a pneumaticdelivery means and apparatus for measuring and determining the [52] U.S.CI ..139/127 P length of weft yarn fed thereto. The apparatus is [51]Int. Cl. ..D03d 47/30,]303d 47/34 adapted to pull a length of yarn' froma supply, in

of Search cyclic action and the ame under tension Sal/RUE of mow/M beingfed to the pneumatic means.

8 Claims, 5 Drawing Figures PATENTE W22 I973 SHEET 1 OF 2 INVENTORWAD/M1 R SVA TX 71/ ORNEYU J MEASURING AND LENGTH DETERMINING MEANS FORWEFT YARN IN SHUTTLELESS LOOMS BACKGROUND OF INVENTION The presentinvention relates to apparatus for fabrics and in particular to ashuttleless loom.

While shuttleless weaving looms, in which the weft yarn is thrown by ajet of high pressure air between the opened warp yarn system of a fabricshed, have become known they have many disadvantages. Such machines havelimited width, low speed, poor efficiency, and little versatility.Attempts to overcome these disadvantages have been tried. For examplelooms with double sheds fed by one inserting device have been suggested.It was necessary however to provide this machine with gripper rods,pivotable needles, or other means to grasp the weft yarn and insert italternatingly in the form of a loop into the opposite sheds.

In any event, the known looms are unsuitable for the production ofweaving apparel since they require the insertion of a double weft andare not adaptable to the production of multicolor or mixed weft feedingas would be necessary for the production of such material as silk andcotton.

When the loom is provided with a double shed and gripper means, themechanism for mounting and operating the gripper means is large andtakes up a large space between the sheds. Consequently, the loom becomesunnecessarily large while the sheds become unnecessarily small. It hasbeen found that the efficiency speed and size of these known machinesare in large measure limited by the pneumatic delivery or insertionsystem and the system for premeasured defined lengths of yarn forinsertion as weft in the warpyarn systems.

It is accordingly the object of the present invention to provide animproved shuttleless loom having increased efficiency, speed, andversatility.

It is the object of the present invention to provide an improvedshuttleless weaving loom capable of fabrics of large widths.

It is another object of the present invention to provide a shuttlelessloom in which weft yarns may be mixed and of different color.

It is an object of the present invention to provide an improvedpneumatic weft yarn insertion device for a shuttleless loom.

It is an object of the present invention to provide an improved systemand apparatus for measuring and feeding defined lengths of yarn to thepneumatic insertion device of a shuttleless loom.

It is another object of the present invention to provide improved meansfor premeasuring and feeding yarn to a double nozzle pneumatic deliverysystem of a shuttleless loom.

It is another object to increase the speed and efficiency of measuringand feeding weft yarn.

These objects, others and numerous advantages will be found in thefollowing disclosure.

In a copending application Ser. No. 79,035 filed on even date herewith,in the name of the same inventor, there is disclosed and claimed a novelpneumatic insertion of a delivery mechanism which may be used inconjunction with the present invention.

SUMMARY OF INVENTION According to the present invention there isprovided a shuttleless loom having pneumatic means for delivering yarnto a fabric shed comprising apparatus for measuring and determining thelength of the yarn. The apparatus comprises selectively operablewithdrawing means interposed between a supply and the delivery means andselectively operable brake means located between the supply and thewithdrawal means. Control means are provided to sequentially operate thebrake and withdrawal means for a predetermined time to pull a definedlength of yarn from the supply.

The withdrawal means may comprise a pair of opposed rollers, however, itpreferably comprises a pulley held between the ends of a cable which isheld at one end by a winch and at the other by a yieldably resilientmember. The yarn passes over the pulley which by being reciprocallypulled withdraws a defined length of yarn from the supply.

BRIEF DESCRIPTION OF THE DRAWINGS In the following disclosure referenceis made to the accompanying drawings wherein:

FIG. 1, is a plan view, partially in section and partially schematic,showing a loom embodying the insertion device and measuring system ofthe present inven tion;

FIG. 2, is view similar to FIG. 1 showing another form of the invention;

FIG. 3, is an enlarged sectional view showing the position of thepneumatic insertion device of the present invention with regard to thewarp system and beat reed;

FIG. 4, is a vertical section through the insertion device of thepresent invention; and

FIG. 5, is an enlarged plan view of the details of the control means forthe insertion device.

DESCRIPTION OF INVENTION Before turning to the disclosure of the presentinvention it is to be understood that the drawings and description giveonly those details of a loom which are new and which are necessary for afull and complete understanding of the present invention. It will beobvious that certain well known details are omitted. Reference toconventional looms, well known texts and literature can be made by thoseskilled in this art to supplement the present disclosure, if that isnecessary.

As seen in FIG. 1 the loom is provided with a common weft feeding andinserting device 1 located transversely between two opposed warp or shedsystems. The inserting device 1 is a pneumatic system which as seen inFIGS. 4 and 5 comprises a reversible nozzle assembly from which extendsa pair of hollow cones 2,2 through the respective orifices 3,3 of whichpass weft yarns 4,4. The yarns are fed through a central opening at thetop of the nozzles assembly by means to be described later.

The cones 2,2 of the nozzle assembly are mounted on a carrier body 5,journalled for rotation upon a bearing 6 which is itself mounted bysuitable screw fasteners to an arm 7. The arm 7 extends cantileveredfrom and is adjustably secured to a longitudinally extending breast beam8. The arm 7 is provided with a channel 9 extending centrally to a pointbeneath a duct 10 which itself extends through the center of both thebearing 6 and carrier 5. A transeverse bore 11 is formed within thecarrier 5, beneath the cones 2, 2, which communicating with the duct 10opens outwardly in the direction of the orifices 3,3. Surrounding eachof the cones 2 and 2 and the respective ends of the bore 11 are conicalfunnel caps 12 and 12 respectively adapted to condense and direct theair about the cones outwardly in a horizontal column from the orifice3,3.

Air is supplied from the source to maintain a volume within the nozzleassembly, to hold the end of the yarn 4, 4 in the orifice 3,3, and atselected time supplied as an impulse jet of high pressure to force andcarry the yarn outwardly into the respective sheds. The supply of thepicking fluid, as seen in FIG. 3, in this particular case the pressureair, to the inserting device 1 is directed by means of a feed line 53and a compressor 54 driven by an electric motor 55, there being a valve56 disposed in the line 53, which is controlled by a solenoid 57. Thesolenoid 57 is connected (FIG. by means of conductors 58 with a switch59 and a source of electric current 60.

A wheel gear 13 is secured about the lower end of the carrier and isengaged by a corresponding segment ratchet 14. The segment ratchet 14 isfixed at the end of a lever 15 pivoted at its other end 15 on the arm 7.The lever 15 is operatively positioned by the core of a solenoid controldevice 16 and a compression spring 17. The solenoid 16 is a conventionalelectromagnetic device capable of retracting or permitting extension ofthe core 16 on the application of an electric current through the coil.Solenoid 16 (FIG. 5) is connected by means of conductors 61 with anotherswitch 62 and also with a source 63 of electric current. Associated withthe switches 59 and 62 are control cams 64 and 65 mounted on a commonshaft, together with the cam 39. Mounted on the same shaft is still acam 66 controlling a switch 67 which by means of conductors 68 closesthe electric circuit for solenoid 69 of the brakes 46, 46' according toFIG. 1, or for solenoid 37, the latter controlling the bell crank 36which supports the feed roller 35, according to FIG. 2. The source ofcurrent switch, or relay means, is conventional. The swing of lever 15and consequently of ratchet 14 is limited by the stop pins 18 and 19which are set so as to enable full movement of the ratchet 14 to rotatethe nozzle assembly by 180.

As seen in FIG. 3 the outer or free end 20 of the arm 7 extends over thebatten 21 of the loom. The batten 21 is mounted on the upper end of alever arm or sword 22, pivoted to the frame of loom at its other end 23.The batten 21 carries a divided reed 24, 24 to beat up the weft yarns4,4 as they are laid into the fabrics sheds 25, 25 produced on the loomto either side of the weft feed assembly. The reed 24,24 is adjustablymounted to the batten 21. As seen in FIG. 1 the arm 7 furthermorecarries temples 26,26 for holding the selvedges of the advancing fabrics25, 25. As seen in the Figures the arm 7 is arranged symmetricallybetween two sheds formed from warp 27, 27 systems forming the fabrics25, 25. In the event fabrics of uneven width are desired, it is onlynecessary to move the arm to the right or left a corresponding distance.

An elongated channel housing member 28 is mounted above the length ofthe breast beam 8. The housing defines an inner space 29 and is coveredby a lid 30. As seen in FIGS. 1 and 2 the channel member 28 houseswithin the space 29 means for withdrawing the weft yarn 4,4 from a pairof bobbins 31, 31 mounted to the side of the loom. The yarns aresimultaneously measured and fed to the nozzle assembly.

To illustrate the principle by which the yarns 4,4 are measured and fedto the nozzle assembly reference is made to FIG. 2. The yarns 4,4 passfrom their respective bobbins 31,31 through a brake 32,32 such as theconventional disk brake, through a comb guide 33, to which the yarnspass disposed at relatively different levels between a pair of feedrollers 34 and 35 to the nozzle cones 2,2. The feed roller 34 is fixedto a shaft, journalled in a stationary bearing and continuously rotatedin the direction shown by the arrow. The second feed roller 35 is freelyjournalled at the end of a bell crank 36, opposite to the roller 34. Asolenoid device 37 is located adjacent the free end of the bell crank 36and is selectively activated by impression of an electric current (froma source not shown). The core 37 is hooked into engagement with theupper free end of the bell crank 36. A compression spring 38 is fixedbetween the lower arm of the bell crank 36 and the frame of the loom tomaintain the roller 35 normally out of contact with the roller 34.

At the instant suitable for the insertion of the weft yarn 4, 4 into thetwo opposed sheds (i.e., when weft feeding is desired) the solenoid 37is energized to extend the core 37 upward in the direction of thenozzle, as seen in FIG. 2 to thereby pivot the bell crank 36 and bringthe two rollers 34 and 35 into engagement. The rollers draw the yarns4,4 from the bobbins 31, 31. At the instant feeding of weft is to ceasethe solenoid 37 is deenergized and the spring 38 pulls the rollers outof engagement. The action of the brakes 32,32 limits the amount of weftwhich can be drawn through the cones 2,2 by the force of the air jetblown through the nozzles. By selectively choosing and adjusting thestrength of the blowing air, the time of roller contact, the degree ofbrake power, the length of the wefts thrown into the opposed sheds canbe adjusted.

For a more accurate and precise weft feeding device, reference is madeto the embodiment shown in FIG. 1. Similarly as in the first case theweft yarn 4, 4 is withdrawn from the bobbins 31, 31 into the housingspace 29. However, to the side of the loom is mounted a rotating cam 39,and a linearly reciprocating rack which engages the gear wheel fixed toa winch drum 41. The rack 40 is provided at one end with a cam followerand is mounted for reciprocal movement but resiliently loaded tomaintain engagement with the cam 39. In this manner rotation of cam 39will reciprocate the rack 40 and oscillate the drum 41, as shown by thedouble arrows.

A cable 42 is wound about the drum 41 and has one end stretched toextend along the housing 29 in a direction tangential to the drum 41 andis provided at its end with a light weight ball preferably made ofplastic such as a table tennis ball. The ball 43 is located in anelongated tube 44 connected at its opposite end to a source of suction.By sucking through the tube 44 on the ball 43 the cable 42 is pulledtaut. By varying the degree of suction on the ball 43 degree of tensionon the cable 42 can be varied.

The yieldably resilient mechanism created by the ball 43 and 44 ishighly accurate and precise. It will how ever be appreciated that othermeans such as a compression spring may also be used at the end of thecable.

Secured to the cable 42 are a pair of eyelets or pully member 45, 45therethrough which the weft threads 4,4 are passed. The pullies 45, 45may be adjustably relative to each other so as to be fixed at differentdistances from the drum 41 or ball 43. Located between the bobbins 31,31 and the pully 45, 45 are a pair of disc brakes 46,46. The brakes 46,46 are preferably jointly controlled by a solenoid device 46 a, to exerta selective braking action or drag on the yarns 4,4. A common coil andcore is provided for the solenoid 46 to insure joint operation ofbrakes. Other automatic or electromechanical braking means may be used.Located between the pullies 45, 45 and the nozzle assembly is a pair ofseparating roller capstans or guides 47 and 47 adapted to be verticallyadjustable. In this manner the yarns 4,4 are removed from theirrespective bobbins, pass through the brakes 46, 46, the pullies 45, 45and thence over the capstans 47, 47 into the cones 2,2 of the nozzleassembly. The electromechanical brakes 46, 46 are adapted to normallyexert a drag on the yarns 4, 4 so that between the brakes and theorifices 3,3 of the nozzle assembly the yarns are held under continuoustension. The brakes are released whenever the yarns are to be unwoundfrom their respective bobbins.

Normally, the guide 47 is arranged below that of the guide 47,conforming to the comb 3, since in order to prevent the weft threads 4,4' from entanglement in their path between the guides 47, 47' and thereversibly rotatable nozzles 1, it is necessary to maintain a certainsense in the relative movements of the nozzles 1. This is based on thefact that the entry point 71 of the nozzles 1 for the weft thread 4 fedfrom the lower guide 47, passes in the course of rotation of the nozzles1 under the other weft thread 4' which is fed to its entry point 71' ofthe nozzles 1 from the upper guide 47', so that during the rotation ofthe nozzles l the two weft threads 4, 4 are being kept vertically apartand do not entangle. The subsequent reverse rotation of the nozzles 1through 180 into their initial position brings also the two weft threads4, 4' into their initial positions.

It will be appreciated the the apparatus as shown is provided withsuitable operating devices such as motors, connecting levers, controlmeans switches, relays etc. to obtain selective sequential andcooperative operation. The mechanism required is conventional andaccordingly has been omitted from the drawing for the sake of moreclearly depicting the present invention.

The operation of this latter embodiment will be clearly seen byfollowing FIG. 1. Starting from the assumption that when the last weftcourse has been laid in or when the weaving process is instituted thepullies 45, 45 are caused to be pulled by suction on ball 43 to theextreme left position and as close to the comb guide 33 as desired. Itis thus the first step to provide a predetermined measured length ofweft yarn. This is accomplished by releasing the brakes 46, 46 and bycausing the winding drum 4] under action of the cam 39 and rack 41 topull the pullies 45, 45 to the right. Because the yarn ends are held incones 2,2 by action of the air blowing therein, the movement of thepullies 45, 45 causes withdrawal of thread 4,4 from their respectivebobbins into the housing 29 in the form of a loop of hairpin shape asseen. The length of the yarn may also be controlled by the initialposition of the ball 43 in the tube 44. When the desired length of yarnis thus obtained, the brakes 46, 46 may be activated, and the windingdrum stopped. The yarns will thus be held under tension between thebrakes 46, 46 and the cones 2,2 of the nozzle assembly, while the sameyarns are loosely held between the bobbins 31 and 31 and the same brakemeans. The forces on the yarn is created by the tensioning devicesformed by the drum mechanism 41 acting on cable 42, on the one hand, andthe ball 43 on the other hand. Variation of either device willselectively change the tension.

The measured yarns are laid into the shed, at instant when the reeds 24,24 are in their most rearward, or non-beat position, and the shed formedin the warp yarns 27 is open, as seen in FIG. 3 for reception of theweft. At this instant a burst of high pressure air is delivered to thenozzle 1 and the pullies 45, 45 are released (by reversal of rack 40) tomove: backward under the effect of suction on the ball 43. The brakes46, 46 are held in full brake position so that the force of air impulsepulls the yarns and deposits them between the warp threads 27 of therespective sheds.

It is obvious that in this manner of feeding the yarns 4, 4 are not onlypremeasured to accurate and precise lengths but the speed of theirdelivery and feed is carefully controlled. This is of particularimportance in order to control and vary the velocity of the insertion ofthe yarns 4,4 into the respective sheds. It is possible by the use ofthis control means to avoid the formation of undesired loops or loopends along the selvedges of the fabric 25, 25. This is accomplished byproviding each yarn with virtually independent measuring and feed means.

The weft yarn 4,4 is normally surrounded by a volume of blowing airthrough the funnel cap 12, 12. When the shed is opened by the retractionof the reeds 24,24 a blast or jet of air under high pressure isimpressed through the nozzle assembly and the weft length is insertedbetween the warp 27. After such insertion the yarns are beaten up bymovement of the reeds to the completed end 48 of the fabric 25, 25. Assoon as the weft is beaten up, and laid into proper position the treadend is cut leaving it suspended in the cone 2,2. Conventional cuttingdevices or thread burning devices 49, 49' comprising a holder and aresistance wire 50 and 50' connected by conductors 51 to a source 52 ofelectric current, are located between the orifices 3, 3' and the febricend 448. On each beat-up of the reed 24 the wires 40 and 51 burn off theweft threads 4, 4'. At this moment it is possible and may be desirablewhen employing different wefts to reverse the nozzle assembly 180, asexplained earlier, so that the yarns 4,4 are interchanged into therespectively opposed fabrics 25 or 25.

While the yarns 4,4 may cross over the opening of the nozzle assemblyduring reversal, the provision of separating capstans, adjustable todifferent heights, prevent any entanglement. The cycle of operation hasthus returned to its initial phase and can begin over again.

The present apparatus has a number of advantages not found in the priorart looms. While conventional devices have been designed to insert weftunder fluid pressure on looms up to to cms the weft insertion device ofthe present invention can be used on looms having width in excess of 3meters which may then approach the size of contemporary gripper looms. Afurther advantage is obtained by the present device with regard to theefficiency of its operation. The present device can work on these widelooms at the same speed (400-500 weft insertions per minute) at whichcontemporary narrow jet looms operate.

A great advantage is obtained from the versatility of the presentweaving loom and the possibility of turning the weft insertion device atthe end of each weft laying in. Thus such fabrics may be easily formed.Because the turning of the nozzle assembly can be selectivelyaccomplished predetermined weft patterns of perhaps multiple (e.g. 10 or12) weft insertions of particular thread may be accomplished. It is notnecessary to turn the assembly after each weft lay in. Two color goodsmay also be easily formed since the present device eliminates the needof handling waiting weft bobbins and gripper means by the simpleexpedient of reversing the nozzle assembly.

The present device also permits the formation of fabrics of unequalwidth. By repositioning the arm 7 along the breast beam 8 as previouslyexplained and by adjustably varying the relative distances between thepullies 45 and 45 for example weft yarns of different length can beobtained.

It will thus be seen that the objects and advantages stated earlier haveall been fulfilled. Other advantages will be clear as well. For example,in addition to being able to weave mixed wefts two or more fabrics withboth different wefts and warps can be made. This is a substantialincrease in versatility over the prior art. The present device providesa more uniform weave eliminating streaking and unevenness common inconventionaly formed fabrics such as silk and cottons. Weft threads ofparticular property can be readily chosen and used. Thus yarns, such aspolyesters or polyamides may be mixed with natural yarns in any desiredpattern.

It will be obvious that various modifications, changes, and equivilantmechanisms can be made to the specific devices shown and described.Because of this the present description is intended to be illustrativeonly of the present invention and should not be taken as limiting in anymanner of its scope.

What is claimed:

1. A shuttleless loom comprising at least one warp shed forming systemand a hollow breast beam extending along the length of said loom,pneumatic means for delivering yarn for the weft thereof, a supply ofyarn, and means for measuring and feeding a determined length of yarn tosaid pneumatic means, said means for measuring said length of yarn beinglocated in said beam, and comprising means for selectively pulling alength of yarn into said beam and brake means for holding said yarn frombeing pulled during feeding of said length to said pneumatic means.

2. The loom according to claim 1 wherein said loom includes a pair ofopposed sheds and said pneumatic delivery means includes means forrespectively delivering a pair of independent yarns to said sheds, andsaid means for measuring and feeding said yarn includes means forpulling and braking said independent yarns in selective sequence.

3. The loom according to claim 2 wherein said pneumatic means isrotatable to deliver yarn to each shed selectively and said measuringand feeding means includes means for maintaining said yarns separatelydur ing said rotation.

4. In a shuttleless loom having pneumatic means for delivering at leastone yarn from a source of supply to the warp system of a fabric shed,apparatus for measuring and determining the length of the yarns fed tosaid delivery means, comprising selectively operable means interposedbetween said supply and said pneumatic means, for withdrawing said yarnfrom said supply, said withdrawing means comprising a pulley mountedbetween opposed tensioning devices, and includes means for causing saidtension devices to exert selectively operating forces on said pulleymeans to withdraw the yarn from the supply, selectively operable brakemeans located between said supply and said withdrawing means, andcontrol means for sequentially operating said brake and withdrawingmeans for predetermined periods to obtain a determined length of yarn.

5. The apparatus according to claim 4 wherein said pulley is interposedbetween the ends of a cable, one end of said cable being wound about arotatable winch, the other end of said cable being secured to yieldablyresilient compression means, and includes means for selectivelyoscillating said winch to cause said pulley to withdraw said yarn incyclical operation.

6. The apparatus according to claim 5 wherein said means for oscillatingsaid winch comprises a circular gear connected to said winch, a rackengaging said gear, said rack having a cam follower at one end and a camengaging said cam follower to cause said rack to reciprocate in apredetermined manner to cause said winch to rotate in periodic reversingdirections.

'7. The apparatus according to claim 5 wherein said yieldably resilientmeans comprises an elongated tube, a source of vacuum applying a suctionto said tube, and wherein said cable is provided with a ball adapted tobe inserted within said tube and subject to said suction force.

8. The apparatus according to claim 4 wherein a pair of yarns aremeasured and two pulleys'are provided, said pulleys being arranged intandem on said cable, and includes means for adjusting the distancebetween said pulleys.

1. A shuttleless loom comprising at least One warp shed forming systemand a hollow breast beam extending along the length of said loom,pneumatic means for delivering yarn for the weft thereof, a supply ofyarn, and means for measuring and feeding a determined length of yarn tosaid pneumatic means, said means for measuring said length of yarn beinglocated in said beam, and comprising means for selectively pulling alength of yarn into said beam and brake means for holding said yarn frombeing pulled during feeding of said length to said pneumatic means. 2.The loom according to claim 1 wherein said loom includes a pair ofopposed sheds and said pneumatic delivery means includes means forrespectively delivering a pair of independent yarns to said sheds, andsaid means for measuring and feeding said yarn includes means forpulling and braking said independent yarns in selective sequence.
 3. Theloom according to claim 2 wherein said pneumatic means is rotatable todeliver yarn to each shed selectively and said measuring and feedingmeans includes means for maintaining said yarns separately during saidrotation.
 4. In a shuttleless loom having pneumatic means for deliveringat least one yarn from a source of supply to the warp system of a fabricshed, apparatus for measuring and determining the length of the yarnsfed to said delivery means, comprising selectively operable meansinterposed between said supply and said pneumatic means, for withdrawingsaid yarn from said supply, said withdrawing means comprising a pulleymounted between opposed tensioning devices, and includes means forcausing said tension devices to exert selectively operating forces onsaid pulley means to withdraw the yarn from the supply, selectivelyoperable brake means located between said supply and said withdrawingmeans, and control means for sequentially operating said brake andwithdrawing means for predetermined periods to obtain a determinedlength of yarn.
 5. The apparatus according to claim 4 wherein saidpulley is interposed between the ends of a cable, one end of said cablebeing wound about a rotatable winch, the other end of said cable beingsecured to yieldably resilient compression means, and includes means forselectively oscillating said winch to cause said pulley to withdraw saidyarn in cyclical operation.
 6. The apparatus according to claim 5wherein said means for oscillating said winch comprises a circular gearconnected to said winch, a rack engaging said gear, said rack having acam follower at one end and a cam engaging said cam follower to causesaid rack to reciprocate in a predetermined manner to cause said winchto rotate in periodic reversing directions.
 7. The apparatus accordingto claim 5 wherein said yieldably resilient means comprises an elongatedtube, a source of vacuum applying a suction to said tube, and whereinsaid cable is provided with a ball adapted to be inserted within saidtube and subject to said suction force.
 8. The apparatus according toclaim 4 wherein a pair of yarns are measured and two pulleys areprovided, said pulleys being arranged in tandem on said cable, andincludes means for adjusting the distance between said pulleys.